The invention relates to an automatic machine for moulding glass articles, such as cups, by means of pressing.
The automatic machines for moulding glass articles by means of pressing which are currently in use usually comprise a station for delivering a gob of glass, a pressing station, and a periodically rotating turntable supporting a plurality of two-part moulds distributed on its periphery, it being possible for the two parts of a given mould to be brought into contact with each other (closed position) or to be separated from each other (open position). A given mould, in the closed position, receives a gob of glass with a weight determined at the delivery station and is then brought to the pressing station where an appropriately shaped plunger is lowered into the mould and shapes the gob of glass to the form of the mould and is then raised so as to free it from the mould. The mould containing the article moulded by means of pressing is subsequently moved by the turntable to the next position where an air-blowing pipe blows air into the moulded article contained in the mould for the purpose of cooling the said article. When the mould, which continues to revolve, arrives at a certain position in which the article is considered to be sufficiently cool to be rigid, the mould is opened and a gripping member grasps the article and directs it to a station for completion of its cooling. A machine of this type normally produces 30 to 40 articles per minute.
The number of moulds present on the turntable may vary from one machine to the other, but is typically 12 to 18 moulds.
These moulds, in particular those for moulding glass, including glass convertible into glass-ceramics, the melting range of which is around 1100.degree. C. or higher, are damaged relatively quickly, hence the frequent need to repair or even replace them. Besides the interruptions in the machine's operation, these repairs and replacements are costly in view of the large number of moulds employed.
Another disadvantage of these multi-mould rotating automatic machines is that it is impossible, in practice, to effect rapid cooling of the moulds and the moulded articles contained therein by circulating water, owing to the rotating nature of the machine, so that they can be cooled only by air cooling, which is less efficient and results in a limited production rate.